Double acting sander head



Dec.9,1989 v ,(,RBANGERTER ETAL- 8,482,38z

DOUBLE ACTING SANDER HEAD Filed Jan. 28, 1966 KEN/VETH R. BNGERTER HROLD F DE W/7' 7' United States Patent O DOUBLE ACTING SANDER HEAD Kenneth R. Bangerter, Ithaca, and Harold F. De Witt, Waverly, N.Y., assignors to Ingersoll-Rand Company,

New York, N.Y., a corporation of New Jersey Filed Jan. 28, 1966, Ser. No. 523,694 Int. Cl. B24b 23/00 U.S. Cl. 51-170 1 Claim ABSTRACT OF THE DISCLOSURE A head for a sander or grinder which provides a choice of either random orbital motion or circular motion. The workhead is mounted in bearings so that it is free to rotate about its own axis when it is eccentric to the output shaft of the power source. The workhead can be moved so that its axis is concentric with the' axis of the output shaft of the power source to provide true circular motion.

This invention relates to an improvement for a power tool such as a rotary Sander or buffer. The invention provides a mechanism adapted to allow the choice of either random orbit motion such as that achieved in U.S. Patent No. 2,794,303 or true nonorbiting circular operation of a sanding or abrading pad.

It is -known that a random orbiting abrasive disc will produce a very smooth finish on a workpiece. It is also known that when it is desired to remove material from the workpiece at a high rate of speed, one way is to use a true nonorbiting or circular motion.

It is therefore one object of this invention to provide a power tool which will allow the choice of either a random orbiting motion or true circular motion for abrading or bufiing.

It is another object of this invention to provide a simple means for changing from random orbiting motion to circular motion for abrading or bufling.

It is a further object of this invention to provide a simple looking means to insure that a true circular motion will be achieved.

It is a still further object of this invention to provide a power tool which allows adjustment of the amount of orbiting thereby varying the surface finish obtainable.

In general, the above objects are carried out by providing an improved power tool which comprses a casing, a motor and a rotor or rotating shaft. Attached to the shaft is a housing. The longitudinal axis of the housing is concentric to the axis of the output shaft of the motor. A spindle is provided with one end mounted in the housing and a disc for attaching an abrasive or buffing pad is attached to the other end of the spindle. The spindle is mounted so that it is capable of being selectively positioned within the housing so that the axis of the spindle is either concentric or eccentric to the axis of the member which attaches the housing to the rotary output of the motor. When the axis of the spindle is eccentric to the axis of attaching member, the spindle and thus the pad is free to rotate about its own axis. When the axis of the spindle is concentric to the axis of the housing, a pin engages the upper end of the spindle. The spindle is then locked in position with respect to the housing and rotates with the housing about the axis of the attaching member. The disc thus rotates in a true circular motion.

If desired, the invention may take the form of an attachment for any tool such as a drill or conventional sander or buifer.

In the drawings:

FIG. 1 is a ve'rtical elevation of the attachment in a position so that a true random orbit is achieved;

Patented Dec. 9, 1969 ICC FIG. 2 is a cross-sectional view taken on the line 2-2 of FIG. 1;

FIG. 3 is a vertical elevation of a portion of a power tool with the attachment similar to FIG. 1 showing the spindle locked in position to give a circular motion of the Pad;

FIG. 4 is a cross-sectional view taken on line 4-4 of FIG. 3.

The improved power tool of this invention has a casing 20 and a motor 21 having a rotor 22. There is a cup shaped housing 1, having an eccentric cylindrical recess, attached to the rotor by a threaded member 2. When the shaft rotates, the housing will also rotate about an axis 15 concentric to the axis of the rotor. A rotatable eccentric 3 is mounted within the' housing 1 and axially retain'ed in the housing by pins 5 and 5'. Within the eccentric there is mounted a bearingv 7 held in place by a retaining ring 4. A spindle 6 is mounted within the bearing 7. The spindle 6 may be hollow to reduce weight. The upper end 8 of the spindle has at least one keying surface such as a flat side but is shown as octagonal. The purpose' of having a keying surface will be explained hereinafter. The lower portion of the spindle 6 has a circular disc or work head 9 attached thereto. An abrasive or buffing pad may be attached to the disc 9 by any suitable means such as a screw or adhesive.

A latch 10 is pvotally mounted to the housing 1. The latch 10 fits into latch detents 11 in the eccentric to prevent rotation of the eccentric relative to the housing. The position of the eccentric 3 with respect to the housing determines the siez of the orbit. There may be provided a plurality of latch detents radially spaced around the eccentric to allow adjustment of the amount of orbit.

There is a locking pin 12 which fits in the housing 1 perpendicular to the axis of rotation of the housing and is horzontally offset from the axis of the housing. The function of this pin Will be explained hereinafter.

The principal features of this invention involve the abilty to change from true random orbiting of the pad to true nonorbiting circular rotation of the pad and the simple locking means for holding the spindle in the desired position.

When the device is in the position shown in FIG. l, the spindle 6 is free to rotate about its own axis 16 which is parallel but laterally displaced from the axis 15 of the housing 1. When the housing rotates about axis 15, axis 16 will orbit about axis 15 thus the pad 9 Will orbit about axis 15. No rotative force of pad 9 about axis 16 will be generated except 'for that which is caused -by the drag of bearing 7, and any -point on pad 9 will follow a generally orbital path. Since the pad is mounted on a bearing 7, when the pad is brought into contact with the workpiece to be abraded or polished, the disc will rotate. During contact, any point on the disc will not travel in a true orbit about the axis 15 but will travel in a random orbit. This random orbit is desrable to produce a fine finish.

When rough work is to be done, it is desrable to remove material rapidly. A good method is conventional circular action. The necessity of using a separate machine or head is removed by this invention. For'conventional circular action, the rotatable eccentric 3 is-rotated degrees from the position shown in FIGS. 1 and 2 to that shown in FIGS. 3 and 4. This is accomplished by releasing the latch 10 and rotating the eccentric 3 relatve to the housing and then pivoting the latch into a latch detent 11. In this position, a locking pin 12 abuts against a keyin'g surface or a flat side 13 on the upper portion of the spindle 6. The locking pin may alternatively be any means for abutting the surface 13 such as a wall of the housing. The greater number of flat sides, the greater the chance of the pin abutting a flat side. This places the axis 16 and w axis 15 in axial alignment and zero orbit. Because locking surface 13 and locking pin 12 abut, the spindle 6, and thus the pad 9 can no longer rotate freely on bearing 7 but is forced to rotate with the housing 1. When the housing is rotated, the disc will rotate in a true circular path as is conventional with disc sanders or buffers.

p Dynamic balance is maintained by the counterweight 14 on the eccentric 3. This counterweight ofsets the weight of the spindle 6 and pad 9 when the device is in the posi tion of FIGS. 1 and 2. The counterWei-ght 14 also acts as a handle for rotating the eccentric 3.

If a smaller orbit is desired, the eccentric may be rotated less than 180 degrees from the position shown in FIGS. 1 and 2, and the latch is pivoted into a latch detent 11. Thus, the size of the Orbit may be changed, and the finish obtainable can be changed.

Broadly, the invention provides a simple apparatus for changing from a random orbit to a true circular motion. More specifically, the invention provides a simple locking means to insure a true circular motion.

This invention may be van integral part of a sander or may be an attachment for any existing power tool such as a drill.

The above description is only an illustration of a preferred embodiment, and the invention is limited only by that which is within the scope of the appended claim.

We claim:

1. A power tool such as a sander or the like comprising:

a casing;

a motor having a rotor;

a housing;

means for attaching said housing to said rotor;

a spindle longitudinally mounted in said housing and having at least one flat side on one end and a disc mounted on the other end of said spindle;

a rotatable eccentric mounted within said housing for positioning the axis of said spindle either concentric or eccentric to the axis of said rotor;

a bearing mounted between said spindle and said rotatable eccentric;

said spindle being free to rotate about its own axis relative to said housing when said axis is eccentric to the axis of said housing;

locking means for preventing said spindle from rotating relative to said housing when the axes of said spindle and shaft are concentric;

a latch pivotally mounted on said housing; and

detents in said rotatable eccentric adapted to receive said latch;

said locking means including a pin horizontally mounted in said housing adapted to engage the flat side of said spindle when the axis of said spindle is concent-ric to the axis of said rotor.

References Cited UNITED STATES PATENTS 2,794,303 6/ 1957 Wickes 51-170 3,035,376 5/ 1962 Szafran 279-6 XR 3,172,241 3/ 1965 Habenicht 51-120 FOREIGN PATENTS 372,040 3/ 1923 Germany. 416,652 7/ 1925 Germany.

HAROLD D. WHITEHEAD, Primary Examiner U.S. Cl. X.R. 5l-120 

